Re: [Qemu-devel] QEMU -netdev vhost=on + -device virtio-net-pci bug

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 10/03/13 20:24, Michael S. Tsirkin wrote:
> On Fri, Mar 08, 2013 at 03:48:04PM +1100, Alexey Kardashevskiy wrote:
>> Michael,
>>
>> Thanks for the fix.
>>
>> There was another question which was lost in the thread.
>>
>> I am testing virtio-net in two ways:
>>
>> Old -net interface:
>> -net tap,ifname=tap0,script=qemu-ifup.sh \
>> -net nic,model=virtio,addr=0:0:0
>>
>> (qemu) info network
>> hub 0
>>   \ virtio-net-pci.0:
>> index=0,type=nic,model=virtio-net-pci,macaddr=52:54:00:12:34:56
>>   \ tap.0: index=0,type=tap,ifname=tap0,script=qemu-ifup.sh,downscript=/etc/qemu-ifdown
>>
>> New -netdev interface:
>> -netdev tap,id=tapnet,ifname=tap0,script=qemu-ifup.sh \
>> -device virtio-net-pci,netdev=tapnet,addr=0.0
>>
>> (qemu) info network
>> virtio-net-pci.0:
>> index=0,type=nic,model=virtio-net-pci,macaddr=52:54:00:12:34:56
>>   \ tapnet: index=0,type=tap,ifname=tap0,script=qemu-ifup.sh,downscript=/etc/qemu-ifdown
>>
>>
>> I get very different virtio0 device features and speed (70MB/s vs.
>> 700MB/s). I guess somehow the "hub 0" is responsible but there is no
>> way to avoid it.
>>
>> Is there any way to speed up the virtio-net using the old -net interface?
>
> Not at the moment. Why do you want to use it?


It is not like I really want it, I was just trying to understand (now it is
more or less clear) why exactly "not" as the documentation is saying about 
-net and -netdev as synonyms while they are not.



-- 
Alexey